1. Field of the Invention
The present invention relates to a color image recording and reproducing system and, more particularly, to a color image recording and reproducing system using a color matching technique for matching display colors displayed under different ambient illumination conditions in a color matching technique of matching the color of a target object and its display color.
2. Description of the Related Art
Conventionally, accurate color reproduction is not taken into consideration in a television (TV) system for transmitting and reproducing a photographed color image. Only a visual image quality in reproduction is considered.
To reproduce an image photographed at a remote place with accurate colors, it is not sufficient to process the image by the camera to the display system without any distortion and error. The image must be reproduced in the environment wherein the image is illuminated by a light source having the same spectrum as that on the photographing side.
However, it is actually very difficult to prepare an illumination having the same spectrum on the photographing and reproduction sides.
In a technique of matching "three-dimensional" colors under almost the same conditions as those of three stimulus values represented by R, G, and B in order to perform color matching, which is known as a prior art, it is difficult that the color matching results accurately coincide with each other.
The reason is that there are color matching conditions.
More specifically, even if the spectrum is the same, a so-called XYZ colorimetric system, i.e., three color matching functions (color matching functions of an XYZ colorimetric system), like the ones shown in FIG. 8, are actually present as a human visual function. Actually, the spectrum is multiplied by this function to calculate an integrated value.
For this reason, even when a color is visually observed as a given color under a certain illumination, if the spectrum distribution changes, this color is observed as another color under another illumination.
Various attempts have been made to obtain the colors of printed matter or colors displayed on a TV monitor to be closer to colors visually recognized by man.
On the other hand, as the DTP system (Desk-ToP publishing; electronic publishing) has been spread with recent higher-performance and smaller-size computers, color matching techniques (e.g., Jpn. Pat. Appln. KOKAI Publication Nos. 5-216452 and 6-51732) of matching the colors of printed matter as an input/output target with display colors displayed on a TV monitor have been proposed.
These prior arts disclose a color matching technique of matching the colors of printed matter as an input/output target with display colors displayed on a TV monitor under various different ambient illumination conditions.
In either prior art, the display and printing places are assumed to be at the same point, i.e., under the same illumination conditions. These prior arts do not particularly disclose or indicate a technique of, e.g., reproducing by display or printing an image photographed at, e.g., a different remote place apart from a reproduction place with accurate color reproduction, i.e., matching the color of a reproduced object, i.e., the color of a display screen or printed matter with the color of the photographed object under different illumination conditions.
Originally, if a color image recording and reproducing system having the same transmission characteristics as the above-described three human visual properties is constructed, the color of a reproduced image is seen to be the same as the color of an object. However, since the visual properties vary due to individual differences, the color of the reproduced image and the color of the object are not always matched with each other for all people.
To completely match the color of the reproduced image with the color of the object in consideration of these situations (so as to allow an observer to perceive these colors as the same color), necessity for matching the spectra is required.